Fuel injector

Abstract

A fuel injector for direct injection of fuel into a combustion chamber includes: a housing having at least one combustion chamber-side injection aperture; a linearly movable valve needle for opening and closing the injection aperture; a solenoid; an armature which is linearly movable by the solenoid; and a first sleeve attached to the armature. A first stop surface facing away from the combustion chamber is formed on the first sleeve, and a second stop surface facing the combustion chamber is formed on the valve needle, the first and second stop surfaces striking one another when the valve needle and/or the armature is/are moved linearly.

What is claimed is: 
     
       1. A fuel injector for direct injection of fuel into a combustion chamber, comprising:
 a housing having at least one combustion-chamber side injection aperture; 
 a linearly movable valve needle for opening and closing the injection aperture; 
 a solenoid; 
 an armature which is linearly movable by the solenoid; and 
 a first sleeve, the first sleeve being formed as a hollow, tubular component having a constant inside and outside diameter; 
 wherein the first sleeve is a separate component and the first sleeve is attached to the armature; 
 wherein a first stop surface facing away from the combustion chamber is formed on the first sleeve, and a second stop surface facing the combustion chamber is formed on the valve needle, the first and second stop surfaces striking one another when at least one of the valve needle and the armature is moved linearly; and 
 wherein the armature has a continuous recess and the first sleeve is situated on a wall of the recess; 
 wherein a groove is formed in the wall of the recess, and wherein the first sleeve is situated in the groove 
 and further comprising a second sleeve attached to a base body of the valve needle, wherein the second stop surface is formed on the second sleeve; 
 wherein a total length of the first sleeve and the second sleeve, measured parallel to a longitudinal axis of the fuel injector, has a same value as a length of the recess. 
 
     
     
       2. The fuel injector as recited in  claim 1 , wherein the recess has a uniform diameter over the entire length of the recess. 
     
     
       3. The fuel injector as recited in  claim 1 , wherein the first sleeve protrudes beyond the wall of the recess. 
     
     
       4. The fuel injector as recited in  claim 1 , wherein the groove is open on a side of the armature facing away from the combustion chamber. 
     
     
       5. The fuel injector as recited in  claim 1 , wherein at least one of:
 the first sleeve is made from a more solid material than the armature; and the second sleeve is made from a more solid material than the remaining components of the valve needle. 
 
     
     
       6. The fuel injector as recited in  claim 1 , wherein at least one of:
 the first sleeve is attached to the armature in at least one of a form-locked manner, a friction-fit manner, and an integrally joined manner; and 
 the second sleeve is attached to the valve needle in at least one of a form-locked manner, a friction-fit manner, and an integrally joined manner. 
 
     
     
       7. The fuel injector as recited in  claim 1 , wherein the first sleeve and the wall of a recess are in contact along the linear axis of the fuel injector. 
     
     
       8. A fuel injector for direct injection of fuel into a combustion chamber, comprising:
 a housing having at least one combustion-chamber side injection aperture; 
 a linearly movable valve needle for opening and closing the injection aperture; a solenoid; 
 an armature which is linearly movable by the solenoid; and 
 a first sleeve, the first sleeve is formed as a hollow, tubular component having a constant inside and outside diameter; 
 wherein the first sleeve is a separate component and the first sleeve is attached to the armature; 
 wherein a first stop surface facing away from the combustion chamber is formed on the first sleeve, and a second stop surface facing the combustion chamber is formed on the valve needle, the first and second stop surfaces striking one another when at least one of the valve needle and the armature is moved linearly; and 
 wherein the armature has a continuous recess and the first sleeve is situated on a wall of the recess, 
 wherein the first sleeve is a harder material than the armature; 
 wherein a groove is formed in the wall of the recess, and wherein the first sleeve is situated in the groove 
 and further comprising a second sleeve attached to a base body of the valve needle, wherein the second stop surface is formed on the second sleeve; 
 wherein a total length of the first sleeve and the second sleeve, measured parallel to a longitudinal axis of the fuel injector, has a same value as a length of the recess. 
 
     
     
       9. The fuel injector as recited in  claim 1 , wherein the first sleeve is situated in the recess of the armature, wherein the first stop surface of the first sleeve and the second stop surface of the valve needle lie in an interior of the recess. 
     
     
       10. The fuel injector for direct injection of fuel into a combustion chamber as recited in  claim 8 , wherein the first sleeve is situated in the recess of the armature, wherein the first stop surface of the first sleeve and the second stop surface of the valve needle lie in an interior of the recess.